An air cart is an agricultural pneumatic conveying implement which includes a system for blending of air and particulate material, such as seed or fertilizer, for entrainment into an air stream for conveyance to one or more distribution channels. Certain air carts, such as found on the Flexi-coil 20, 30 and 50 Series Models, combine air and particulate material in a manifold structure connected to a meter and numerous associated hoses or conveying tubes. A controlled output rate is achieved by metering directly into separate air flow tubes. In the manifold two or more products may be mixed for simultaneous delivery or maintained in separate streams. The air cart manifold provides more accurate metering to the delivery conduits of the delivery tool for consistent product application rates across the delivery tool. In contrast, other air carts have only a single delivery tube from which product is divided through a dividing header into multiple delivery tubes in the delivery tool. Using a series of dividing headers to separate the product stream repeatedly shocks the product, particularly seed, and the dividing process is more random resulting in less even product distribution.
An air cart can have a number of different product tanks with separate meters and manifold tubes. For each meter a series of tubes is provided in the manifold to carry air and product to delivery tubes of the delivery tool. Within the manifold, communication valves permit mixing product between tubes. It is periodically necessary to remove the manifold for access to the metering wheels for conducting adjustments, rate calibration and meter wheel changes. Conveniently, the manifold is constructed as a unitary assembly which can be positioned with a single connect or disconnect operation to avoid numerous tedious individual connections. The manifold connection for distribution of the particulate carrying air streams through a number of distribution channels is necessarily substantially air tight.
Since the meter area, including the tank outlets of the air cart, is essentially blocked by the manifold, additional problems are encountered removing excess particulate material after use to empty the tanks. Conventional air carts unduly raise the height of the air cart in order to provide clearance under the cart for access of an auger hopper to catch and convey material emptied from the tank. Raising the cart height raises its center of gravity and increases the possibility of overturn operating in uneven terrain. Further, conventional carts allow the emptied material to fall by gravity over the conveyance tubes or hoses of the manifold. This is an untidy process which is inconvenient and results in some product loss.
Smaller air carts with one or two tanks and meters, such as Flexicoil 20 Series and 30 Series, have manual handling mechanisms to lower the manifold for access. In one design a sling and winch are provided to lower the manifold. This provides access to the meters, but is cumbersome for calibration and unloading. Calibration involves collecting and weighing a volume of seed or other material metered from a defined number of rotations into a bag which must rest on the lowered manifold. With the manifold suspended from the cart, it is awkward and difficult to position the collection bags. Tanks must also be unloaded after use by allowing the material to spill over the manifold, and some product will be deflected and lost. The manifold in the lowered position in the sling provides only limited access for a small collection hopper.
An alternative prior design provides a hand crank mechanism for manually lowering the manifold. The manifold is further supported by rollers on a frame which permit the manifold to be rolled in tracks longitudinally or transversely. The manifold can also be rotated about the central supporting crank screw. This range of movement allows the manifold to be shifted from the area or meter where access is needed. The manifold is raised again into position by the hand crank. This design provides more access than the sling design, but it is not possible to shift the manifold completely from the underside to provide access. The roller carriage is a permanent obstruction which causes some difficulty for maintenance. It also requires significant effort to lower and raise the manifold manually. A single point connection like the crank screw does not work well for a large manifold like the three meter design. Flexure across the manifold would make sealing contact difficult at the extreme ends. A two point connection would be needed for reliable action adding more obstructing structure to the undercarriage.
Particularly for a large air cart with three or more tanks and associated meters, the manifold is quite large and heavy. A tier of channels is provided for each meter in the manifold with communication valves between them for mixing any combination of the products. In place in operational position, the manifold obstructs access to the meters for set up, calibration or maintenance. The manifold is particularly heavy for manual handling. In addition the central pivot and rolling bearings of the prior art mechanism would not fully expose a central meter to change meter wheels or calibrate flow.
An automated mechanism is desired to lower the manifold to a service position which provides clear access for maintenance, calibration and unloading to the meters and air cart under carriage, and to accurately and automatically replace it in operational position for full sealing contact at each of the manifold inputs, which would eliminate heavy manual positioning.